WASHINGTON — The Pentagon calls the stockpile an “active reserve.” Others call it a hidden nuclear arsenal. International arms control treaties do not apply to it and officials rarely discuss it publicly. But now, the nation’s backup supply of nuclear weapons may be next up for major cuts.
For the first time a member of the Joint Chiefs of Staff is suggesting the United States’ nuclear weapons reserve is too large and becoming too expensive to maintain.
“We have more backup systems in terms of weapons systems than we actually have deployed,” General Norton A. Schwartz, chief of staff of the Air Force, told the Globe in a recent interview. “Some of that is a reasonable hedge [but] there is probably room for reductions.’’
The call by Schwartz to consider cutting the stockpile is supported by the findings of a report cowritten in May by retired Marine Corps general James Cartright, who had been in charge of all nuclear weapons. The report recommended that the United States during the next 10 years reduce its nuclear force to a total of 900 weapons, half of them on alert and half in reserve.
An offer to substantially reduce the reserve arsenal, arms control specialists said, could be a bargaining chip in future negotiations with Russia, which considers the arsenal a threat to the nuclear parity that is central to ensuring stability between the two former foes.
Cartright’s report indicates that the US arsenal of reserve warheads is about 2,800 — significantly larger than the deployed force, which is about 1,700 warheads mounted in silos, aboard submarines, and available to be dropped from aircraft. Russia has about 2,000 warheads in reserve.
The size of the reserve stock is a legacy of the Cold War, when the United States and the Soviet Union, locked in a global nuclear standoff, maintained tens of thousands of warheads in the event of an all-out nuclear exchange. Having a large reserve was considered an insurance policy against the possibility that the weapons on alert might malfunction or the remote possibility that a surprise attack could wipe out US silos and nuclear bomber bases.
Both countries are steadily reducing their deployed forces; the weapons now on alert, for example, are slated to come down to no more than 1,550 by 2018 under a treaty with Russia.
Any move to substantially cut the US nuclear reserves probably will bring strong opposition from members of Congress with nuclear weapons contractors in their districts. Opposition is also expected from some national security experts who think the United States must maintain overwhelming nuclear superiority to deter nations like Iran believed to be seeking nuclear weapons, and ensure smaller nuclear powers like China do not try to reach parity.
A third group has argued that the large US arsenal is also needed to guarantee the security of dozens of US allies without nuclear arms.
In a critique published this month, Mark Schneider of the National Institute for Public Policy said relying on a substantially smaller arsenal of deployed and reserve weapons akin to the Cartwright proposals would be too risky.
“This smaller, less-ready force will be tasked with deterring or defeating a difficult and toughening set of targets,” wrote Schneider, a former Pentagon director of strategic defense.
Thus far, the backup systems — in the form of different types of warheads stored at air and naval bases — have received little attention even though arms control specialists maintain they remain destabilizing.
Russia views the larger US reserve arsenal as a particular threat and has kept its own stockpiles high in response, said Daryl Kimball, executive director of the Arms Control Association, a nonpartisan Washington think tank.
Russia has also maintained a larger arsenal of smaller, tactical nuclear arms for battlefield use. The United States could trade reductions in its reserve stocks for cuts in Russia’s tactical weapons, Kimball said.
There is also a mounting financial incentive to reduce the stockpile.
On average, the weapons — the US military maintains seven types of nuclear warheads — are several decades old and require upgrades to ensure their reliability and safety. Additional measures are taken to ensure they are not vulnerable to sabotage or theft.
“We can save money and logistics costs if we could get at the reserve,” said Jon Wolfsthal, who until last spring served as a top adviser to Vice President Joe Biden on arms control and nonproliferation.
Cartright’s report said there is little strategic value in having so many warheads. The current overall stockpiles “vastly exceed what is needed to satisfy reasonable requirements of deterrence between the two countries as well as vis-à-vis third countries whose nuclear arsenals pale in comparison quantitatively,” said the report, published by Global Zero, an international coalition seeking to eliminate nuclear weapons.
“The deployed forces of 450 warheads would be de-alerted and require a small number of days [24-72 hours] to become launch ready,” it added. “Most of the 450 reserve warheads could be taken from storage and loaded on delivery vehicles within weeks to months.”
The White House is studying the prospects for dramatic new reductions in the overall arsenal, according to officials knowledgable about the review.
Kimball said he believes in the next round of US-Russian reductions, the Obama administration wants the next agreement to address not just deployed weapons but also the backup stocks. But that would require some key decisions that the administration and Congress have been unwilling to do, experts say.
For one, the United States needs more capacity to dismantle nuclear weapons. A facility in Amarillo, Texas, is now upgrading the warheads for the active force as well as destroying older weapons.
“We are running that dismantlement program at full capacity,” Schwartz said.
But Wolfsthal, who is now deputy director of the James Martin Center for Nonproliferation at the Monterey Institute of International Studies, estimates that the dismantlement capacity could be swiftly increased at the Texas facility, known as Pantex, for a fraction of the cost to maintain and upgrade the reserve weapons.
For example, he said, it will cost roughly $10 billion during the next decade to upgrade the inventory of B-61, the primary thermonuclear weapon in the US arsenal.
“For 1 percent of that you could speed up dismantlement by half,” he said. “You can dismantle them quick if we spend a little more but no one has taken on that issue.”Bryan Bender can be reached at email@example.com.